1. Technical Field of the Invention
The present invention generally relates to telecommunications and data communications networks. More particularly, and not by way of any limitation, the present invention is directed to a protection scheme for such networks under multiple failures.
2. Description of Related Art
A network operator typically takes into consideration multiple objectives when routing traffic through a network. One objective may be to minimize cost. Another objective may be to minimize transmission impairments. A third objective may be to maximize the possibility that the network can be restored using a backup path in the event of a failure thereof.
Generally, there are three types of restoration schemes: dedicated restoration, shared restoration, and best effort restoration. In dedicated restoration, the capacity of a protection, or restoration, path is reserved for an individual demand. In shared restoration, the restoration capacity is reserved, but shared across multiple demands. In best effort restoration, no reservation is made and restoration capacity is allocated in real time on an as-available basis. The first two classes of restoration both have guaranteed restoration in the event of a single failure; however, they differ in restoration time, as shared restoration requires real-time path setup.
Whereas intelligent mesh routing techniques have been available for computing a backup path in a 1:N or M:N shared restoration scheme, such techniques tend to be inadequate where multiple failures are encountered in a network. Further, known protection path implementations do not address the issue of correlated multiple failures, especially in the context of applicable network resource constraints.